The broad objectives are to develop and refine methods for examining human chromosomes, work toward a fuller understanding of these methods and apply them to meaningful questions relating to human chromosome structure, function and behavior. More specifically, our aims are to investigate: (1) Qualitative and quantitative chromosome banding methodology to (a) refine, simplify and standardize chromosome banding procedures; (b) investigate mechanisms underlying the banding procedures; and (c) use quantitative methods such as semi-automated densitometry to measure variants in individual bands. (2) Chromosome polymorphisms to (a) detect chromosome polymorphisms, especially those in interstitial and terminal regions, using benign ovarian teratomas and monozygotic twin families; and (b) study the heritability of those polymorphisms; and (3) Position effect to obtain (a) cytologic evidence, by (1) somatic cell chromosome rearrangements such as the Burkitt's lymphoma 8/14 translocation and the ataxia-telangiectasia -/14 translocation and (2) "balanced" meiotic chromosome rearrangements in retarded, malformed children and (b) genetic evidence, by studying single gene markers in somatic and meiotic chromosome aberrations which are candidates for position effect; (4) Selected major chromosome rearrangements to learn more about them. Techniques will include cell culture, prophase and prometaphase cell preparations, chromosome banding, light and fluorescent photomicroscopy, semi-automated densitometry and photometry, methods of fixing, extracting and histochemically staining specific chromosome components. Single gene marker studies will be done.